question re original EH 16 second delay

[john ettinger <john.ettinger@gmail.com>]

Kind of obscure question regarding the original 1980s EH 16 second delay. Is there any significance to the different colors of print on these? Some have green some have red. Maybe date of production? features? materials? etc.
Haven't yet found an explanation for that anywhere so any help would be very much appreciated!

Thanks,

John